Tantalum-containing material removal

ABSTRACT

Methods are described herein for etching tantalum-containing films with various potential additives while still retaining other desirable patterned substrate portions. The methods include exposing a tantalum-containing film to a chlorine-containing precursor (e.g. Cl 2 ) with a concurrent plasma. The plasma-excited chlorine-containing precursor selectively etches the tantalum-containing film and other industrially-desirable additives. Chlorine is then removed from the substrate processing region. A hydrogen-containing precursor (e.g. H 2 ) is delivered to the substrate processing region (also with plasma excitation) to produce a relatively even and residue-free tantalum-containing surface. The methods presented remove tantalum while retaining materials elsewhere on the patterned substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Prov. Pat. App. No.62/529,976 filed Jul. 7, 2017, and titled “TANTALUM-CONTAINING MATERIALREMOVAL” by Wang et al. The disclosure of 62/529,976 is herebyincorporated by reference in its entirety for all purposes.

FIELD

Embodiments disclosed herein relate to gas-phase etchingtantalum-containing materials.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess which etches one material faster than another helping e.g. apattern transfer process proceed. Such an etch process is said to beselective to the first material. As a result of the diversity ofmaterials, circuits and processes, etch processes have been developedwith a selectivity towards a variety of materials.

Dry etch processes are often desirable for selectively removing materialfrom semiconductor substrates. The desirability stems from the abilityto gently remove material from miniature structures with minimalphysical disturbance. Dry etch processes also allow the etch rate to beabruptly stopped by removing the gas phase reagents. Some dry-etchprocesses involve the exposure of a substrate to remote plasmaby-products formed from one or more precursors. For example, remoteplasma excitation of ammonia and nitrogen trifluoride enables siliconoxide to be selectively removed from a patterned substrate when theplasma effluents are flowed into the substrate processing region. Remoteplasma etch processes have recently been developed to selectively removeseveral dielectrics relative to one another. However, dry-etch processesare still needed, which delicately yet quickly remove metals which havelimited or no previously known chemically volatile pathways.

SUMMARY

Methods are described herein for etching tantalum-containing filmshaving various potential additives while still retaining other desirablepatterned substrate portions. The methods include exposing atantalum-containing film to a chlorine-containing precursor (e.g. Cl₂)with a concurrent plasma. The plasma-excited chlorine-containingprecursor selectively etches the tantalum-containing film which mayinclude other industrially-desirable additives. Chlorine is then removedfrom the substrate processing region. A hydrogen-containing precursor(e.g. H₂) is delivered to the substrate processing region (also withplasma excitation) to produce a relatively even and residue-freepost-etch tantalum-containing surface. The methods presented removetantalum while retaining the other exposed materials. The sequentialexposure to chlorine-containing precursor and then hydrogen-containingprecursor was found achieve a smooth residue-free tantalum-containingsurface. A thin tantalum oxide layer may be initially present on thesurface of the tantalum-containing layer, in which case a local hydrogenplasma may be used to reduce or remove the tantalum oxide prior to theexposure to the chlorine-containing precursor. All the recited steps maybe performed in the same substrate processing chamber in some cases.

Exemplary processes described herein include methods of removingtantalum-containing films. The methods include placing the substrateinto a substrate processing region. The substrate includes exposedtantalum-containing material. The methods further include etching thetantalum-containing material by flowing a halogen-containing precursorinto the substrate processing region while forming a halogen localplasma from the halogen-containing precursor and forminghalogen-containing plasma effluents. Etching the tantalum-containingmaterial further includes accelerating the halogen-containing plasmaeffluents towards the substrate by biasing the halogen local plasmarelative to the substrate. Etching the tantalum-containing materialleaves a residue on a remaining portion of the substrate. The methodsfurther include removing the residue from the remaining portion of thesubstrate by flowing a hydrogen-containing precursor into the (same)substrate processing region while forming a hydrogen local plasma fromthe hydrogen-containing precursor to form hydrogen-containing plasmaeffluents. The methods further include flowing of thehydrogen-containing precursor occurs after flowing thehalogen-containing precursor. The methods further include removing thesubstrate from the substrate processing region. The tantalum-containingmaterial may further include silicon, carbon, and aluminum. Atemperature of the substrate while removing the tantalum-containingmaterial may be between 80° C. and 450° C. while removingtantalum-containing material from the substrate. The substrate may bemaintained at a same substrate temperature while etching thetantalum-containing material and removing the residue.

The present technology may also encompass additional methods of etchingtantalum-containing material from a substrate. The additional methodsinclude placing the substrate into a first substrate processing region.The substrate includes tantalum-containing material and an overlyingtantalum oxide. The methods further include reducing the overlyingtantalum oxide and exposing the tantalum-containing material by flowinga hydrogen-containing precursor into a first substrate processing regionhousing the substrate while forming a hydrogen plasma in the firstsubstrate processing region. The methods further include placing thesubstrate into a second substrate processing region. The methods furtherinclude etching the tantalum-containing material by flowing ahalogen-containing precursor into the second substrate processing regionwhile forming a local halogen plasma from the halogen-containingprecursor to form halogen-containing plasma effluents. Forming the localhalogen plasma further includes accelerating the halogen-containingplasma effluents towards the substrate by biasing the local halogenplasma relative to the substrate. The methods further include flowing ahydrogen-containing precursor into the second substrate processingregion while forming a second hydrogen plasma in the second substrateprocessing region. Flowing of the hydrogen-containing precursor occursafter flowing the halogen-containing precursor. The methods furtherinclude removing the substrate from the second substrate processingregion. a temperature of the substrate while removing thetantalum-containing material is between 175° C. and 275° C. whileremoving tantalum-containing material from the substrate.

In some embodiments, the tantalum-containing material may have at least40% atomic percent tantalum. The tantalum-containing material may haveat least 50% atomic percent tantalum. The tantalum-containing materialincludes tantalum, silicon, carbon and aluminum. The hydrogen-containingprecursor may include Hz. The halogen-containing precursor may includeat least one of chlorine or bromine. The halogen-containing precursormay be a homonuclear diatomic halogen. The first substrate processingregion and the second substrate processing region are the same substrateprocessing region. A pressure within the first substrate processingregion and the second substrate processing region may be between 0.01Torr and 10 Torr during one or more of flowing the hydrogen-containingprecursor, flowing the halogen-containing precursor or flowing thehydrogen-containing precursor. Forming the hydrogen plasma may includeapplying a local capacitive plasma RF power between a showerhead and thesubstrate. A processing temperature of the substrate may be greater than80° C. during the etching of the tantalum-containing material.

The present technology may also encompass additional methods of etchingtantalum-containing material from a substrate. The additional methodsinclude etching tantalum-containing material and tantalum oxide. Theadditional methods include transferring a substrate into a substrateprocessing region. The substrate includes tantalum-containing materialand a thin tantalum oxide layer thereon. The methods further includeremoving the thin tantalum oxide layer by flowing a hydrogen-containingprecursor into the substrate processing region while forming a localplasma from the hydrogen-containing precursor. The methods furtherinclude etching the tantalum-containing material by flowing achlorine-containing precursor into the substrate processing region whileforming a chlorine plasma from the chlorine-containing precursor to formchlorine-containing plasma effluents. Etching the tantalum-containingmaterial occurs after removing the thin tantalum oxide layer. Themethods further include removing any unreacted chlorine-containingprecursor and other process effluents by purging the substrateprocessing region with an inert gas. Etching the tantalum-containingmaterial leaves a residue on a post-etch surface. The methods furtherinclude removing the residue from the post-etch surface by flowing asecond hydrogen-containing precursor into the substrate processingregion while forming a second local plasma from the secondhydrogen-containing precursor. The methods further include transferringthe substrate out of the substrate processing region. Forming a chlorineplasma may include accelerating the chlorine-containing plasma effluentstowards the substrate by biasing the chlorine plasma relative to thesubstrate. The substrate may be maintained at a same substratetemperature during the removal of the thin tantalum oxide layer and theremoval of the tantalum-containing material. The substrate may remaininside the same substrate processing region throughout the method.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the embodiments. The features and advantagesof the embodiments may be realized and attained by means of theinstrumentalities, combinations, and methods described in thespecification.

DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the embodimentsmay be realized by reference to the remaining portions of thespecification and the drawings.

FIG. 1 is a flow chart of a tantalum-containing film etch processaccording to embodiments.

FIG. 2 is a flow chart of a tantalum-containing film etch processaccording to embodiments.

FIG. 3 shows a schematic cross-sectional view of a substrate processingchamber according to the disclosed technology.

FIG. 4 shows a top plan view of an exemplary substrate processing systemaccording to the disclosed technology.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a letterthat distinguishes among the similar components. If only the referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same reference labelirrespective of the letter.

DETAILED DESCRIPTION

Methods are described herein for etching tantalum-containing filmshaving various potential additives while still retaining other desirablepatterned substrate portions. The methods include exposing atantalum-containing film to a chlorine-containing precursor (e.g. Cl₂)with a concurrent plasma. The plasma-excited chlorine-containingprecursor selectively etches the tantalum-containing film which mayinclude other industrially-desirable additives. Chlorine is then removedfrom the substrate processing region. A hydrogen-containing precursor(e.g. H₂) is delivered to the substrate processing region (also withplasma excitation) to remove chlorine-containing residue and produce arelatively even and residue-free post-etch tantalum-containing surface.The methods presented remove tantalum while retaining the other exposedmaterials. The sequential exposure to chlorine-containing precursor andthen hydrogen-containing precursor was found achieve a smoothresidue-free tantalum-containing surface. A thin tantalum oxide layermay be initially present on the surface of the tantalum-containinglayer, in which case a local hydrogen plasma may be used to reduce orremove the tantalum oxide prior to the exposure to thechlorine-containing precursor. All the recited steps may be performed inthe same substrate processing chamber in some cases.

In order to better understand and appreciate the embodiments disclosedherein, reference is now made to FIG. 1 is a flow chart of atantalum-containing material etch process 1001 according to embodiments.Benefits of the processes described herein include a uniform post-etchtantalum-containing surface while also achieving a high removal rate. Afurther benefit of the tantalum-containing material etch processesdescribed herein results from using the same substrate processing regionfor both the pretreatment, chlorination and post-treatment operations.The benefits resulting from these methods include much higher throughputresulting from reduced wafer handling and high etch rate. The higherthroughput garners a lower cost-of-ownership resulting from the greaterthroughput and the reduced square footage required to house the varioussubstrate processing chambers.

The substrate is placed into a first substrate processing region inoperation 1010. The substrate has portions of tantalum-containing filmand tantalum oxide. Hydrogen (H₂) is flowed into the first substrateprocessing region in operation 1020. A plasma is ignited in the firstsubstrate processing region to react plasma effluents with thesubstrate. The plasma effluents react with the tantalum oxide inoperation 1030. The tantalum oxide is reduced or removed from atop thetantalum-containing film in the process. The substrate is transferredinto a second substrate processing region in operation 1040. Inembodiments, no substrate transfer is necessary because the samesubstrate processing region may be used for all etch operationsdescribed herein. Chlorine (Cl₂) is flowed into the second substrateprocessing region to etch the tantalum-containing film in operation 1050during which a biased local plasma is formed from the chlorine in thesecond substrate processing region. The plasma bias directs ionizedspecies in the plasma effluents toward the substrate. Thebias-accelerated chlorine plasma effluents remove near-surface portionsof the tantalum-containing film and even out the chlorine reactionsacross the substrate. The substrate is then exposed to ahydrogen-containing precursor excited within a biased local plasma toremove any non-volatile etch by-products from atop thetantalum-containing film in operation 1060. Biasing the local hydrogenplasma is optional for both hydrogen operations 1060 and 1020/1030. Thesubstrate is then removed from the second substrate processing region inoperation 1070.

FIG. 2 is a flow chart of a tantalum-containing material etch process2001 according to embodiments. In this example, the tantalum-containingmaterial comprises tantalum, silicon, carbon, and aluminum. Thetantalum-containing material may consist of tantalum, silicon, carbon,and aluminum according to embodiments. Benefits of the processesrepresented in FIG. 2 also include a uniformtantalum-silicon-carbon-aluminum surface after processing, low waferhandling overhead, and a rapid etch rate. The substrate is placed into asubstrate processing region in operation 2010. All of the operationsoccur in the same substrate processing region in embodiments. Thesubstrate has portions of the tantalum-containing film and an oxidelayer potentially overlying the tantalum-containing film in embodiments.The oxide layer may comprise tantalum and oxygen according toembodiments. Hydrogen (H₂) is flowed into the substrate processingregion in operation 2020. Operation 2020 is optional and used if anoxide layer is present on the tantalum-containing film. An absence ofatmospheric exposure in advanced wafer handling configurations couldconceivably result in an absence of any overlying oxide layer accordingto embodiments. If the oxide layer is present, a plasma is ignited inthe first substrate processing region to react plasma effluents with thesubstrate. The plasma effluents may react with the oxide layer in(optional) operation 2030. Operation 2030 may include an optional biasplasma power as before. The oxide layer is reduced and/or removed fromatop the tantalum-containing film in the process and exposes thetantalum-containing film.

The substrate may then remain in the same substrate processing region ormay be transferred to another substrate processing region for thechlorine operation. Chlorine (Cl₂) is flowed into the substrateprocessing region in operation 2040. Also in operation 2040, a localplasma is formed from the chlorine in the substrate processing region. Abias may be applied to the local plasma to further direct ionizedspecies in the plasma effluents toward the substrate. The chlorineplasma effluents etch the tantalum-containing film and produce arelatively even post-etch surface. Exposure of the tantalum-containingmaterial to the chlorine-containing plasma effluents is thought to formvolatile chlorine-containing complexes on the surface including as theetch proceeds. The volatile chlorine-containing complexes desorb readilyat the conditions described herein without any stimulation other thanthe energy from the adsorption reaction and the temperature of thesubstrate. The volatile chlorine-containing complexes may include TaCl₅,SiCl₄, CCl_((x)), and AlCl₃ according to embodiments. The carboncomplexes (CCl or CCl_(x)) may be less volatile and so may be removedwith the assistance of operations 2020-2030 as well as 2050 to bedescribed shortly (e.g. in the hydrogen operations before or followingoperation 2040). Fluorine-containing precursors were not found to beeffective in removing the tantalum-containing film because some of thefluorine-containing complexes were not volatile, and deleteriouslyremained on the surface as a consequence. The chlorine-containing plasmaeffluents were found, fortuitously, to produce volatilechlorine-containing complexes from each of the industrially relevantcomplexes formed from tantalum, silicon, aluminum and carbon. Theremoval rate of each of the elemental components (Ta, Si, C, and Al) ofthe tantalum-containing film was also found to be high enough forindustrial applications. The hafnium chloride complexes are inferred tobe beneficially nonvolatile and allow the retention of exposed gatematerial while each of tantalum, silicon, carbon, and aluminum arereadily removed from exposed tantalum-containing material. At theconclusion of operation 2040, some chlorine residue may remain on thesurface of the tantalum-containing material.

The substrate is not transferred out of the substrate processing regionbetween operations 2040 and 2050 in embodiments. The substrate mayremain in the same placement for operation 2050 according toembodiments. The substrate is then exposed to a hydrogen-containingprecursor (also excited in a local plasma) to remove any non-volatilepost-etch residues which remain atop the tantalum-containing film inoperation 2050. The hydrogen plasma of operation 2050 may be biased inembodiments. Operations 2040 and 2050 may be repeated as a sequence (seedashed line) to remove additional material but may both be carried outin the same substrate processing chamber so transfer overhead does notslow down the throughput. The substrate may then be removed from thesubstrate processing region in operation 2060 once a target amount ofexposed tantalum-containing film has been removed. Optional operation2020 and operation 2050 each involve exposing the substrate to aplasma-excited hydrogen-containing precursor. Either or both of theseoperations may provide the further benefit of removing carbon from thetantalum-silicon-carbon-aluminum material. The additional carbon removalmechanism helps maintain a high etch rate since the carbon chlorideswere found to be somewhat less volatile compared to the chlorides oftantalum, silicon, and aluminum.

The etch process has been found to not etch or not significantly removehafnium oxide (HfO₂), silicon oxide (SiO₂) and tungsten (W) which isbeneficial to several process flows according to embodiments. Hafniumchloride complexes and tungsten chloride complexes may be nonvolatileand remain on the surface of the patterned substrate under theconditions described herein. The ability to simultaneously removetantalum, silicon, carbon, and aluminum contrasts sharply with theinability to remove hafnium oxide, silicon oxide or tungsten and enablesthe processes described and claimed herein. The etch processes describedherein have been found to also etch titanium nitride in addition toetching the tantalum-silicon-carbon-aluminum, which fortuitously enablesremoval of a lining layer combined on the border of thetantalum-containing films described herein. Titanium chloride complexesmay be volatile, in embodiments, within the process conditions describedherein.

Additional aspects of the processes described herein will be presentedbefore and during the description of exemplary substrate processinghardware. Other sources of hydrogen may be used to augment or replacethe molecular hydrogen used to reduce the tantalum oxide and expose thetantalum-containing film. In general, a hydrogen-containing precursormay be flowed into the substrate processing region and thehydrogen-containing precursor may be oxygen-free and/or carbon-freeaccording to embodiments. The hydrogen plasma effluents may be formed ina local plasma and react with the substrate to reduce, etch or removethe tantalum oxide from atop the tantalum-containing film inembodiments. The tantalum-containing film may be oxygen-free. Exposureof the substrate to the hydrogen plasma effluents may result in a fastersubsequent tantalum-containing film etch rate in tantalum-containingfilm etch processes described herein by removing tantalum oxide andexposing tantalum-containing material.

A hydrogen-containing precursor may be used during the pre-treatment andduring the cycled post-treatment occurring after exposure to thechlorine-containing precursor. In both cases, the hydrogen-containingprecursor may be hydrogen (H₂) in embodiments. During thepost-treatment, the hydrogen-containing precursor may be flowed into thesubstrate processing region after the operation of flowing thechlorine-containing precursor in embodiments. Chlorine may be removedfrom the substrate processing region before flowing thehydrogen-containing precursor into the substrate processing region tomaintain a beneficial separate between the precursors. The substrateprocessing region may be actively purged with a relatively inert gasbefore flowing the hydrogen-containing precursor or after flowing thehydrogen-containing precursor to avoid having the hydrogen-containingprecursor react with the chlorine-containing precursor. Operations 1050and 1060 may be repeated, with these precautions, between 1 and 10 timesor between 2 and 7 times to remove additional material rapidly and stillachieve a relatively smooth and even post-etch surface. Operations 2040and 2050 may be repeated between 1 and 10 times or between 2 and 7 timesfor the same purposes. The reaction between the hydrogen-containingprecursor and the chlorine-containing precursor may produce undesirabledeposition and accumulation on the substrate or processing systemhardware in embodiments. As a consequence, the hydrogen-containingprecursor and the chlorine-containing precursor may not be in thesubstrate processing region at the same time according to embodiments.

In general, a halogen-containing precursor may be used in place of thechlorine-containing precursor (e.g. Cl₂) of tantalum etch processesdescribed herein. The halogen-containing precursor may include at leastone of chlorine or bromine in embodiments. The halogen-containingprecursor may be a diatomic halogen, a homonuclear diatomic halogen or aheteronuclear diatomic halogen according to embodiments. In all methodsdescribed herein, the tantalum-containing material may have at least 40%atomic percent tantalum, at least 45% atomic percent tantalum, or atleast 50% atomic percent tantalum in embodiments.

In embodiments, the chlorine-containing precursor (e.g. Cl₂) may beflowed into the substrate processing region at a flow rate of between 3sccm (standard cubic centimeters per minute) and 50 sccm or between 5sccm and 20 sccm in embodiments. The method also includes applyingenergy to the chlorine-containing precursor in the substrate processingregion to form the biased chlorine plasma. The plasma in the substrateprocessing region may be generated using a variety of techniques (e.g.,radio frequency excitations, capacitively-coupled power and/orinductively coupled power). In an embodiment, the energy is appliedusing a capacitively-coupled plasma unit. The plasma power applied tothe chlorine-containing precursor may be between 25 watts and 1500watts, between 100 watts and 1200 watts or between 150 watts and 700watts according to embodiments. An optional sputtering component of theplasma is included to help even out the net tantalum-containing materialetch rate and to hasten the chlorine reaction with thetantalum-containing material on the surface. The chlorine plasma in thesubstrate processing region may be referred to herein as a local plasma.

A local plasma (optionally biased) may be used to excite thehydrogen-containing precursors and the chlorine-containing precursorsdescribed herein. Alternatively, a remote plasma may be used for any ofthe hydrogen steps of the tantalum-containing film etch operationsdescribed. During remote plasma excitation, the substrate processingregion may be devoid of plasma or “plasma-free” during the flow of thehydrogen-containing precursor of the appropriate operations. Inembodiments, a plasma-free substrate processing region means there isessentially no concentration of ionized species and free electronswithin the substrate processing region. Stated another way, the electrontemperature in the substrate processing region may be less than 0.5 eV,less than 0.45 eV, less than 0.4 eV, or less than 0.35 eV according toembodiments. Moreover, the hydrogen-containing precursor may not havebeen excited in any remote plasma before entering the substrateprocessing region in embodiments.

In embodiments, the hydrogen-containing precursor (e.g. H₂) may beflowed into the substrate processing region at a flow rate of between 50sccm and 2,000 sccm or between 100 sccm and 1,000 sccm in embodiments.The method includes applying energy to the hydrogen-containing precursorin the remote plasma region and/or the substrate processing region toform a hydrogen plasma. The plasma in the remote plasma region and/orthe substrate processing region may be generated using a variety oftechniques (e.g., radio frequency excitations, capacitively-coupledpower and/or inductively coupled power). In an embodiment, the energy isapplied to the substrate processing region using a capacitively-coupledplasma unit which biases ions relative to the substrate and acceleratesthe ions towards the substrate. The plasma power applied to thehydrogen-containing precursor in either the remote plasma region or thesubstrate processing region may be between 25 watts and 1500 watts,between 100 watts and 1200 watts or between 150 watts and 700 wattsaccording to embodiments. A sputtering component of the plasma may beincluded to help remove tantalum oxide and chlorinate tantalum in theappropriate operations described previously. The hydrogen plasma and thebiased chlorine plasma in the substrate processing regions may bereferred to herein as local plasmas or bias plasmas.

During the operations of processing the tantalum oxide, the operationsof flowing the halogen-containing precursor to form the tantalum halide,and/or the operation of flowing the hydrogen-containing precursor toremove the tantalum halide, the substrate may be maintained at a samesubstrate temperature in embodiments. During the operations of reducingthe tantalum oxide, etching the tantalum-containing film or removing thechlorine residue, the substrate temperature may be between 80° C. and450° C. in general. In embodiments, the temperature of the substrateduring the operations described may be greater than 80° C., greater than100° C., greater than 120° C., or greater than 150° C. The substratetemperatures may be less than 450° C., less than 400° C., less than 350°C., or less than 300° C. according to embodiments. In a preferredembodiments, the temperature of the substrate during operations 1050 and2040 may be between 175° C. and 275° C. or between 200° C. and 250° C.These temperature ranges enable the volatility of tantalum, silicon,carbon and aluminum chlorine-containing complexes without “turning on”the volatility of the hafnium and oxygen chlorine-containing complexes.The pressure in the substrate processing during any or all of the stepsmay be below 20 Torr, and may be below 15 Torr, below 5 Torr or below 3Torr. For example, the pressure may be between 10 mTorr and 10 Torrduring processing.

Additional process parameters are disclosed in the course of describingan exemplary processing chamber and system. FIG. 3 is a partial crosssectional view showing an exemplary substrate processing chamber 3001which may be used to perform portions of processes described herein. Thevarious precursors (e.g. the hydrogen-containing precursors or thechlorine-containing precursor) may be introduced through one or moreapertures 3051 into the remote plasma region 3065. The precursors may ormay not be excited by the remote plasma power source 3046, inembodiments, as appropriate for the process operations described indetail above. RF power from the remote plasma power source 3046 may beapplied between the remote electrode 3045 and the showerhead 3020 toform a remote plasma in the remote plasma region 3065. The substrateprocessing chamber 3001 includes the chamber body 3012 and the substratepedestal 3010. The substrate pedestal 3010 is at least partiallydisposed within the chamber body 3012. The showerhead 3020 is disposedbetween the remote plasma region 3065 and the substrate processingregion 3040. A local plasma may be formed and biased relative to thesubstrate 3011 by applying RF power from the local plasma power source3048 to the showerhead 3020 relative to the substrate pedestal 3010 inembodiments.

The substrate processing chamber 3001 may include a vacuum pump 3025 anda throttle valve 3027 to regulate the flow of gases through thesubstrate processing chamber 3001 and the substrate processing region3040 therein. The vacuum pump 3025 is coupled through the chamber body3012 and in fluid communication with the interior of the substrateprocessing chamber 3001. The RF power, when applied between the remoteelectrode 3045 and the showerhead 3020, generates a plasma of reactivespecies in the remote plasma region 3065. The remote electrode 3045 issupported by the top plate 3050 and is electrically isolated therefromby the electrically isolating ring(s) 3047. The substrate 3020 issupported by the showerhead flange 3022 and is electrically isolatedtherefrom by the showerhead isolator 3021. RF power, when appliedbetween the showerhead 3020 and the substrate pedestal 3010, generates aplasma of reactive species in the substrate processing region 3040. Theplasma in the substrate processing region 3040 may be referred to as alocal plasma and may be biased to accelerate ions in the substrateprocessing region 3040 towards the substrate 3011 during processing.

A local plasma may be formed to excite the hydrogen-containing precursorin embodiments. Another local plasma may be formed to excite thechlorine-containing precursor according to embodiments. A remote plasmamay or may not be used to further pre-excite the hydrogen-containingprecursor and/or the chlorine-containing precursor in embodiments.

The substrate temperature may be controlled by applying heat to orcooling the substrate pedestal 3010. Substrate temperatures during thevarious operations were given previously. Flowrates of the variousprecursors and process pressures in the substrate processing region 3040and the remote plasma region 3065 were given previously. Apertures inthe showerhead 3020 may be large enough that the pressures in thesubstrate processing region 3040 and the remote plasma region 3065 maybe about the same in embodiments. Plasma power (remote and local) can besupplied from the remote plasma power source 3046 and the local plasmapower source 3048 at a variety of frequencies or a combination ofmultiple frequencies. The RF frequency applied in the exemplaryprocessing system may be an RF frequency of 13.56 MHz but may alsogenerate other frequencies alone or in combination with the 13.56 MHzfrequency. The RF frequency applied in the exemplary processing systemmay be an RF frequency less than 200 kHz, an RF frequency between 5 MHzand 25 MHz, or a microwave frequency greater than 1 GHz in embodiments.The remote and/or local plasma power may be capacitively-coupled (CCP)or inductively-coupled (ICP) into the remote plasma region and/or thesubstrate processing region, respectively. Plasma power may also besimultaneously applied to both the remote plasma region 3065 and thesubstrate processing region 3040 during etching operations describedherein. The frequencies and powers above apply to each region separatelyregardless of whether both regions contain plasma or only one regioncontains plasma.

A plasma may be ignited in the remote plasma region 3065 above theshowerhead 3020 and/or the substrate processing region 3040 below theshowerhead 3020 in embodiments. A plasma may be present in the remoteplasma region 3065 to produce plasma-excited hydrogen-containingprecursors from an inflow of a hydrogen-containing precursor. A localplasma has also been found to work for the pretreatment orpost-treatment using a hydrogen-containing precursor. Thehydrogen-containing precursor may be flowed into substrate processingregion 3040 and a local plasma may be formed to perform the pretreatmentor the post-treatment. The etch cycle may be performed in the samesubstrate processing region.

Embodiments of the processing chambers may be incorporated into largerfabrication systems for producing integrated circuit chips. FIG. 4 showsone such processing system 4001 of deposition, etching, baking, andcuring chambers according to embodiments. In the figure, a pair of frontopening unified pods (load lock chambers 4002) supply substrates of avariety of sizes that are received by the robotic arms 4004 and placedinto a low pressure holding area 4006 before being placed into one ofthe substrate processing chambers 4008 a-f. A second robotic arm 4010may be used to transport the substrate wafers from the holding area 4006to the substrate processing chambers 4008 a-f and back. Each substrateprocessing chamber 4008 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, orientation, and othersubstrate processes.

As used herein “substrate” may be a support substrate with or withoutlayers formed thereon. The patterned substrate may be an insulator or asemiconductor of a variety of doping concentrations and profiles andmay, for example, be a semiconductor substrate of the type used in themanufacture of integrated circuits. Exposed “silicon” of the patternedsubstrate is predominantly Si but may include minority concentrations ofother elemental constituents such as nitrogen, oxygen, hydrogen orcarbon. Exposed “tantalum” of the patterned substrate may bepredominantly tantalum in some cases but may include minorityconcentrations of other elemental constituents such as oxygen, hydrogenand carbon. For example, “exposed tantalum-silicon-carbon-aluminum” maycomprise or consist of tantalum, silicon, carbon and aluminum. Ofcourse, “exposed tantalum” may consist of only tantalum. Exposed“silicon nitride” of the patterned substrate is predominantly Si₃N₄ butmay include minority concentrations of other elemental constituents suchas oxygen, hydrogen and carbon. “Exposed silicon nitride” may consist ofsilicon and nitrogen. Exposed “silicon oxide” of the patterned substrateis predominantly SiO₂ but may include minority concentrations of otherelemental constituents such as nitrogen, hydrogen and carbon. In someembodiments, silicon oxide films etched using the methods disclosedherein consist of silicon and oxygen. “Tantalum oxide” may bepredominantly tantalum and oxygen but may include minorityconcentrations of other elemental constituents such as nitrogen,hydrogen and carbon. Tantalum oxide may consist of tantalum and oxygen.“Tantalum-containing films” may be predominantly tantalum, silicon,aluminum and carbon but may include minority concentrations of otherelemental constituents such as nitrogen and hydrogen.Tantalum-containing films may consist of tantalum, silicon, aluminum andcarbon.

The term “precursor” is used to refer to any process gas which takespart in a reaction to either remove material from or deposit materialonto a surface. “Plasma effluents” describe gas exiting from the chamberplasma region and entering the substrate processing region. Plasmaeffluents are in an “excited state” wherein at least some of the gasmolecules are in vibrationally-excited, dissociated and/or ionizedstates. A “radical precursor” is used to describe plasma effluents (agas in an excited state which is exiting a plasma) which participate ina reaction to either remove material from or deposit material on asurface. “Radical-chlorine” are radical precursors which containchlorine but may contain other elemental constituents. The phrase “inertgas” refers to any gas which does not form chemical bonds when etchingor being incorporated into a film. Exemplary inert gases include noblegases but may include other gases so long as no chemical bonds areformed when (typically) trace amounts are trapped in a film.

The terms “gap” and “trench” are used throughout with no implicationthat the etched geometry has a large horizontal aspect ratio. Viewedfrom above the surface, trenches may appear circular, oval, polygonal,rectangular, or a variety of other shapes. A trench may be in the shapeof a moat around an island of material. The term “via” is used to referto a low aspect ratio trench (as viewed from above) which may or may notbe filled with metal to form a vertical electrical connection. As usedherein, a conformal etch process refers to a generally uniform removalof material on a surface in the same shape as the surface, i.e., thesurface of the etched layer and the pre-etch surface are generallyparallel. A person having ordinary skill in the art will recognize thatthe etched interface likely cannot be 100% conformal and thus the term“generally” allows for acceptable tolerances. “Top” and “Up” will beused herein to describe portions/directions perpendicularly distal fromthe substrate plane and further away from the center of mass of thesubstrate in the perpendicular direction. “Vertical” will be used todescribe items aligned in the “Up” direction towards the “Top”. Othersimilar terms may be used whose meanings will now be clear. The verticalmemory hole may be circular as viewed from above.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theembodiments. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent technology. Accordingly, the above description should not betaken as limiting the scope of the technology. Additionally, methods orprocesses may be described as sequential or in steps, but it is to beunderstood that the operations may be performed concurrently, or indifferent orders than listed.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Anynarrower range between any stated values or unstated intervening valuesin a stated range and any other stated or intervening value in thatstated range is encompassed. The upper and lower limits of those smallerranges may independently be included or excluded in the range, and eachrange where either, neither, or both limits are included in the smallerranges is also encompassed within the technology, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a precursor” includes aplurality of such precursors, and reference to “the layer” includesreference to one or more layers and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

The invention claimed is:
 1. A method of etching tantalum-containingmaterial from a substrate, the method comprising: placing the substrateinto a substrate processing region, wherein the substrate comprisesexposed tantalum-containing material, exposed titanium nitride, andexposed hafnium oxide; etching the tantalum-containing material and thetitanium nitride by flowing diatomic chlorine into the substrateprocessing region while forming a local plasma from the diatomicchlorine and forming chlorine plasma effluents, wherein etching thetantalum-containing material and the titanium nitride further comprisesaccelerating the chlorine plasma effluents towards the substrate bybiasing the local plasma relative to the substrate, wherein etching thetantalum-containing material and the titanium-nitride leaves a residueon a remaining portion of the substrate, and wherein the hafnium oxideis substantially maintained during the etching; removing the residuefrom the remaining portion of the substrate by flowing ahydrogen-containing precursor into the (same) substrate processingregion while forming a hydrogen local plasma from thehydrogen-containing precursor to form hydrogen-containing plasmaeffluents, wherein flowing of the hydrogen-containing precursor occursafter flowing the diatomic chlorine; and removing the substrate from thesubstrate processing region.
 2. The method of claim 1 wherein thetantalum-containing material further comprises silicon, carbon, andaluminum.
 3. The method of claim 1 wherein a temperature of thesubstrate while removing the tantalum-containing material is between 80°C. and 450° C. while removing tantalum-containing material from thesubstrate.
 4. The method of claim 1 wherein the substrate is maintainedat a same substrate temperature while etching the tantalum-containingmaterial and removing the residue.
 5. A method of etchingtantalum-containing material from a substrate, the method comprising:placing the substrate into a first substrate processing region, whereinthe substrate comprises tantalum-containing material and an overlyingtantalum oxide; reducing the overlying tantalum oxide and exposing thetantalum-containing material and a titanium nitride by flowing ahydrogen-containing precursor into a first substrate processing regionhousing the substrate while forming a hydrogen plasma in the firstsubstrate processing region; placing the substrate into a secondsubstrate processing region; etching the tantalum-containing materialand the titanium nitride by flowing a chlorine-containing precursor intothe second substrate processing region while forming a local plasma fromthe chlorine-containing precursor to form chlorine-containing plasmaeffluents, wherein forming the local plasma further comprisesaccelerating the chlorine-containing plasma effluents towards thesubstrate by biasing the local plasma relative to the substrate, whereinthe second substrate processing region is maintained between about 3Torr and about 20 Torr during the etching; flowing a hydrogen-containingprecursor into the second substrate processing region while forming asecond hydrogen plasma in the second substrate processing region,wherein flowing of the hydrogen-containing precursor occurs afterflowing the chlorine-containing precursor; and removing the substratefrom the second substrate processing region.
 6. The method of claim 5wherein a temperature of the substrate while removing thetantalum-containing material is between 175° C. and 275° C. whileremoving tantalum-containing material from the substrate.
 7. The methodof claim 5 wherein the tantalum-containing material has at least 40%atomic percent tantalum.
 8. The method of claim 5 wherein thetantalum-containing material has at least 50% atomic percent tantalum.9. The method of claim 5 wherein the tantalum-containing materialcomprises tantalum, silicon, carbon and aluminum.
 10. The method ofclaim 5 wherein the hydrogen-containing precursor comprises Hz.
 11. Themethod of claim 5 wherein the first substrate processing region and thesecond substrate processing region are the same substrate processingregion.
 12. The method of claim 5 wherein a pressure within the firstsubstrate processing region and the second substrate processing regionis between 0.01 Torr and 10 Torr during one or more of flowing thehydrogen-containing precursor, flowing the halogen-containing precursoror flowing the hydrogen-containing precursor.
 13. The method of claim 5wherein forming the hydrogen plasma comprises applying a localcapacitive plasma RF power between a showerhead and the substrate. 14.The method of claim 5 wherein a processing temperature of the substrateis greater than 80° C. during the etching of the tantalum-containingmaterial.
 15. A method of etching tantalum-containing material andtantalum oxide, the method comprising: transferring a substrate into asubstrate processing region, wherein the substrate comprisestantalum-containing material and a thin tantalum oxide layer thereon;removing the thin tantalum oxide layer by flowing a hydrogen-containingprecursor into the substrate processing region while forming a localplasma from the hydrogen-containing precursor; etching thetantalum-containing material and an exposed titanium nitride by flowinga chlorine-containing precursor into the substrate processing regionwhile forming a chlorine plasma from the chlorine-containing precursorto form chlorine-containing plasma effluents, wherein etching thetantalum-containing material occurs after removing the thin tantalumoxide layer, wherein removing the tantalum-containing material leaves aresidue on a post-etch surface of the tantalum-containing material,wherein the substrate processing region is maintained at a pressurebetween about 3 Torr and about 20 Torr during the etching, wherein thesubstrate further comprises an exposed hafnium oxide, and wherein theexposed hafnium oxide is substantially maintained during the etching;removing the chlorine-containing precursor by purging the substrateprocessing region with an inert gas; removing the residue from thepost-etch surface by flowing a second hydrogen-containing precursor intothe substrate processing region while forming a second local plasma fromthe second hydrogen-containing precursor; and transferring the substrateout of the substrate processing region.
 16. The method of claim 15wherein forming a chlorine plasma comprises accelerating thechlorine-containing plasma effluents towards the substrate by biasingthe chlorine plasma relative to the substrate.
 17. The method of claim15 wherein the substrate is maintained at a same substrate temperatureduring the removal of the thin tantalum oxide layer and the removal ofthe tantalum-containing material.
 18. The method of claim 15 wherein thesubstrate remains inside the substrate processing region throughout themethod.